The VIA chip is very useful in many protocols in the serial mode, but the used channels are CB1 CB2, unavailable on the printer port, in spite of this, we can connect all Orics on the parralel bus, and connect a little EPROM interface on the expansion port like Fabrice-F PCB with an 'almost' same BA...

Like this ? https://fr.aliexpress.com/item/10PCS-DC3-34-Pin-2x17Pin-Right-Angle-Double-Row-Pitch-2-54mm-Double-spaced-Pin-Male/32830491398.html?ws_ab_test=searchweb0_0,searchweb201602_1_10152_10065_10151_10344_10068_10345_10342_10343_10340_10341_10541_10562_10084_10083_10305_10304_10307_10306_10177_...

I am not agree with you Godzil, indeed, we can use a rectifier for each regulator, that will make a schematic respectful of electronic theory, but sometimes, when the manufacturers want to make a low cost device, they use the middle point of the transformer, who is not oscillating despite the appear...

As I can see on the picture the transformer is a classic one with two coils connected in serial mode and the output is in the same configuration, the middle output connection is used for a symetric rectifier, then I suppose that the transformer gives the same voltage in the output (for ex 2x 9v).......